Abstract
Boron/epoxy laminates are used in aircraft and space vehicles for their high strength. Evaluation of stresses and residual strength of the laminate with square cutout are not analyzed in the literature. The present work is focused on studying the effect of hole orientation and laminate geometry on Boron/Epoxy composites laminates under in-plane loading. The analytical solution for stresses around holes in laminates is derived using Savins’s complex variables method to consider a multilayered plate with different hole shapes and orientations of loading. The basic equations of failure criteria available for plain laminates are derived to calculate the residual strength of the laminates with hole using the stresses obtained from the analytical solution. The derived analytical solution is validated by reproducing exactly the same results of earlier researchers even by other formulations and also by the results of finite element analysis using ANSYS. The [0/0]s laminate is not preferred due to highest stress concentrations at the corners that range between 12 to 12.45. Similarly, [45/-45]s laminate is also not preferred due to its higher values of stress concentrations which range from 9.5 to 28. The normalized stress for [0/90]s underx-axis loading is 9.6 and fory-axis loading it is 9.5 which is almost the same. Even for equi-biaxial loading, it is 8.5 and for shear loading, it is 12.45. Except for shear loading, [0/90]s laminate seems to be a better choice for a reasonable value of stress concentration for any general case loading. The analytical solution derived in the present work is the most general and unique as it can yield the stresses around any shape of hole and laminate geometry and all types of in plane loading. This solution will be able to reproduce the results of all other solutions available in the literature by different formulations.
Highlights
Composite materials are very important in manufacturing processes because they are used widely in several areas such as aerospace industries and airframes and thanks to its remarkable strength and stiffness to weight ratios as well as its good resistance to corrosion and the fatigue [1, 2]
The High stiffness and strength to weight ratios and its attractive replacement for metallic materials caused it to be used increasingly in many areas of technology including marine, aerospace, automotive and others. These Superior mechanical properties and extensive application of composite materials are achieved by tailoring of material properties through selective choice of orientation, number of stacking sequence of layers that make up composite material [20,21,22]
The present work addresses the determination of the stresses around square holes in symmetric boronepoxy unidirectional, cross ply and angle ply laminates under uni-axial and biaxial tensions and shear loading at infinity and to study the effect of orientation of square hole in [0/0]s, [0/90]s, and [45/45]s boron/epoxy symmetric laminates and type of in plane loading on the residual strength of the laminate
Summary
Composite materials are very important in manufacturing processes because they are used widely in several areas such as aerospace industries and airframes and thanks to its remarkable strength and stiffness to weight ratios as well as its good resistance to corrosion and the fatigue [1, 2]. A major disadvantage of unidirectional composite materials is that they are highly anisotropic One way around this is to form laminates by stacking two or more laminae' on top of each other with various orientations of the fiber direction and the mechanical properties are dependent upon the way the individual layers are stacked i.e. the stacking sequence. The High stiffness and strength to weight ratios and its attractive replacement for metallic materials caused it to be used increasingly in many areas of technology including marine, aerospace, automotive and others These Superior mechanical properties and extensive application of composite materials are achieved by tailoring of material properties through selective choice of orientation, number of stacking sequence of layers that make up composite material [20,21,22]. The present work addresses the determination of the stresses around square holes in symmetric boronepoxy unidirectional, cross ply and angle ply laminates under uni-axial and biaxial tensions and shear loading at infinity and to study the effect of orientation of square hole in [0/0]s, [0/90]s, and [45/45]s boron/epoxy symmetric laminates and type of in plane loading on the residual strength of the laminate
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